<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        a {
            position: absolute;
            top: 0;
            left: 0;
            width: 100px;
            height: 100px;
            background-color: orange;
        }
        
        div {
            position: absolute;
            display: none;
            top: 0;
            left: 0;
            width: 100px;
            height: 100px;
            background-color: aqua;
        }
    </style>
</head>



<a href="#"></a>
<div></div>
<script src="demo/Todolist/js/utils.js"></script>
<script src="10鼠标行为坐标系01.js"></script>
<script>
    //鼠标行为-》坐标系
    var oa = document.getElementsByTagName('a')[0],
        oMenu = document.getElementsByTagName('div')[0]
    dragNclick(oa, oMenu)
</script>

</body>

</html>